Predator Gasser pulsing/scraping noise in tail drive

[Kamikazi]

My P-Gasser has been doing this since I bought it two years ago (from a previous owner) I've fiddled with gear mesh settings and replaced numerous bearings and gears, but it still makes this embarrassing noise.
It's noticeable in this video (http://www.augustoheli.com/videostuff/videoarchive/HelifreakArchive/B/B-Ham06BillMeadorGasser.zip) of Bill Meador's gasser - especially near the end. When hovering side-in it's really loud on mine.

What causes this? I know it's not normal :dontknow

[Billme]

Bearing pops out of the holder on tt...
You can goop them in, or just pop them in, then take a soldering iron and melt the flange at two points.. this will keep the bearing in place...
Bill

[Kamikazi]

Bearing pops out of the holder on tt...
You can goop them in, or just pop them in, then take a soldering iron and melt the flange at two points.. this will keep the bearing in place...
Bill

Hi Bill,

Well, in the front tail transmission the bearings seem to be held captive by the transmission housing itself. Guess I don't quite understand how they can pop out. I have in the past, put just a smidgen of blue loctite on the outer edge of the bearing to ensure the bearing doesn't spin in the transmission housing.
I recently replaced the front bearing in the TT. (But nothing seemed wrong with the one that was in there). I meant to replace both, but the Century manual indicates that both are 5x11... which is what I ordered. Turns out that the rear bearing is actually larger on the OD. I could try replacing that one too, even though it feels fine.
I figure it's pretty hard to diagnose a problem like this without actually seeing the Heli, but the noise in the video is *exactly* the same noise that my machine has made since I got it. (except mine is possibly a little louder).

Greg

[Billme]

The predator has a noisy gear train even when its ok...I would pull the tork tube, and check the bearing, the one next to the rear trans has a habit of coming out if not modified.
yes its hard to find problems over the keyboard... So long if its running smooth, and holding up, is what i go by:)
Bill

[ArthurKnowles]

FWIW, mine is still pretty new. I don't have this problem, but I did use red locktite on all the bearings in the tourque tube or tail drive as the manual suggested to hold the bearings captive on the shafts and in the correct locations.

[Kamikazi]

The bearings in my torque tube have the inner races loctited to the shaft also - they can't slide around. Actually, I've tried TWO different tail booms and bearings/shafts. No change.

I guess I could accept the noise, except that I know they aren't all this way. Also, no other tail shaft heli (of any brand) that I've ever run across makes the noise mine makes.

I hate to say it, but between my grinding Predator and my shaking Swift, I'm not having very good luck with Century Helis. At least with the Swift, the spool-down shaking problem is widespread and well known (but still no solution).

Maybe I need to make a video of my Predator making it's noises and post it to several forums to get some ideas. It seems like I've replaced and or adjusted just about every part that I think could be a possible cause.

[Billme]

Do you have any up and down play on your mast with the P gasser?

[Kamikazi]

Do you have any up and down play on your mast with the P gasser?

Bill - well, yes. I just checked that the other day. I do remember a very small amount. I have to pull the mainshaft this weekend to install a new pinion and main gear (change ratio), so I can tighten it up to zero play when I put it back together. Hadn't thought about that...
I was planning to check the crown gear autohub for runout while it was apart also.

Greg

[ArthurKnowles]

That's a good idea as my Predator has no end play on the main shaft. I just replaced my crown gear as the original dissolved due to too much pressure from the bevel gear. When I rebuilt it, I made sure the parts moved freely. So far it is working well.

As an FYI, I used a bit of grease from Ikarus I bought for my electrics. It is designed for plastic/nylon gears so it does not damage plastic components. I used it on the bevel gears int he tailbox and oiled or greased (using the Greaser) the bearings in the tailbox/tourque tube. I can't say it helped, but it certainly hasn't hurt.

As an FYI, when I lost the 3 x 15 steel pin from my mainshaft and no longer had a constant driven tail my gearbox was really smooth. I was surprised by how well the gear mesh had smoothed out. Now that it is a driven tail you can't feel quite how smooth it is since turning the tail also turns the rotor and its associated mass.

[Billme]

Well, that is your problem most likely...I use a spit collar on the bottom of the mast also.. Makes adjustment so much simpler ..
Bill

[Kamikazi]

I tried snugging up the endplay on the mainshaft (which was very, very small) and it didn't help.
Today I decided to go ahead and pull the mainshaft to install a new maingear and pinion (to change drive ratio) and I found something - but not sure if it's the problem.

The upper and lower bearings on my outer gear autohub (HI6058N) are very notchy - they feel damaged. The lower one is especially bad. The one-way bearing in the middle feels fine however.

Heliworld is out of stock on that part, and knowing the current state of Predator parts, I'm wondering what other options I might have.

Could I use the HI6064 ??? It looks like an upgrade to the original.

I'm not convinced this will solve my noise problem though. I have the noise all the time, not just when the rotorhead is freewheeling.

[Billme]

Because it has a different type, (more expensive) auto clutch... You must have a older kit for sure to still have torrington type bearing.....

[Kamikazi]

I think I was editing the message (removing a question) while you were replying. So, the torrington type bearing is not as good ?
Looks like Heli-world does have the HI6064C combo in stock. I guess I should get it... ?

[Billme]

The torrington doesn't do good with gassers, thats the reason... That was the first thing they changed when the kits came out...Although, some did ok for some, but not for hard 3D..
Is it possible you could get to someone that has one so you could compare? Like I said before, the Predator gear train is known to be noisy..

[Kamikazi]

Is it possible you could get to someone that has one so you could compare? Like I said before, the Predator gear train is known to be noisy..

I've never run into anyone at a funfly or anything. But I think there are folks within a few hours drive of where I live in Central Penna that own them.
I'll have to look around a little more...